US6300562B1 - Self-sealing telecommunications enclosure - Google Patents

Abstract

A sealed fiber optic enclosure assembly includes a fiber optic enclosure having an inner rim, and an end cap shaped to fit the enclosure. The end cap has a pliable membrane depending from it. The membrane is approximately a cylindrical structure. The membrane may have a wedge-shaped cross section. The wedge-shaped cross section may have an elbow in it. The membrane and end cap may be formed from a single piece of a pliable material, such as polypropylene. The membrane extends into the rim of the enclosure when the end cap is in place on the enclosure. The enclosure has a neck that transitions from a first diameter to a second diameter smaller than the first diameter. The second diameter is smaller than a diameter of the membrane. A clamp is placed over mating portions of the enclosure and end cap, for clamping the end cap to the enclosure. The clamp may be a V-clamp. Pressure is introduced to the enclosure. The membrane is forced against the rim when the enclosure is pressurized, to form a seal between the membrane and the rim. A gap is present between the membrane and a neck portion of the rim before the enclosure is pressurized. The membrane moves to bridge the gap when the enclosure is pressurized. The integrity of the seal can be verified by visually inspecting the enclosure to check whether the end cap is inserted in the enclosure.

Description

FIELD OF THE INVENTION

The present invention relates to telecommunications equipment generally, and more specifically to enclosures suitable for communications cables, such as optical fiber cables.

DESCRIPTION OF THE RELATED ART

Optical fiber communication networks have gained wide acceptance in place of the use of electrical cable systems, due to the significantly enhanced bandwidth capabilities of optical fiber and its immunity to electromagnetic and radiomagnetic interference. Very significant advantages are achievable by the use of optical fiber rather than electrical conduction media. Nevertheless, a continuing problem with the deployment of optical fiber systems is providing a method to terminate optical fiber cables so as to make electrical or optical connections to fibers within the cables while providing adequate environmental protection and allowing for easy installation.

U.S. Pat. No. 5,069,516 to Kohy et al. and U.S. Pat. No. 5,396,575 to Hayward et al. are expressly incorporated by reference herein in their entireties for their teachings on sealed fiber enclosures.

Fiber enclosures are required to be water tight, as they are subjected to a variety of environmental conditions. Such enclosures are frequently deployed underground, and it is important to ensure that water does not come in contact with the optical fiber cables or electronic equipment.

Because there is a need to access the equipment inside the enclosures to reconfigure the equipment following deployment, the enclosures cannot be permanently sealed. Rather, a seal is required that is easily released in order to perform work inside the enclosure, and easy to reseal when the work is completed. It is common to use an o-ring seal in fiber optic enclosures. For a good seal, the end cap must be seated properly in the enclosure. If the end cap is not seated properly, the o-ring may not be water-tight.

A fiber optic enclosure may be mounted on a pole, where it is difficult to visually inspect the enclosure closely to check whether the end cap is aligned precisely on the enclosure. In addition, if particles of dirt or grease are on the o-ring, the o-ring may not seal properly. It is particularly difficult to detect these impurities visually.

Thus, a seal is desired that is reliable, water-tight, and easy to verify.

SUMMARY OF THE INVENTION

The present invention is a sealed telecommunications enclosure and a method for sealing the telecommunications enclosure. An end cap is placed on the telecommunications enclosure. The end cap has a pliable membrane depending therefrom. The membrane extends into a rim of the enclosure when the end cap is in place on the enclosure. The enclosure is pressurized, so as to force the membrane against the rim, thereby forming a seal between the membrane and the rim.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear elevation view of an exemplary enclosure according to the present invention.

FIG. 2 is a side elevation view of the enclosure shown in FIG.1.

FIG. 3 is a cross sectional view of the enclosure of FIG. 1, with a first exemplary end cap partially inserted therein.

FIG. 4 is an enlarged detail of a portion of the enclosure shown in FIG.3.

FIG. 5 is a cross sectional view of the enclosure of FIG. 1, with a second exemplary end cap completely inserted therein.

FIG. 6 is an enlarged detail of a portion of the enclosure shown in FIG.5.

DETAILED DESCRIPTION

The present invention is a self-sealingtelecommunications enclosure assembly100. FIGS. 1 and 2 show theenclosure110, into which fiber and equipment (not shown), are installed. The interior of theenclosure100 may contain a card cage (not shown) having slots for accommodating a plurality of printed circuit boards having electrical circuits and/or electrical/optical transducers (not shown). The electrical circuits may provide a variety of functions, such as processing optical and electrical voice, data, and/or video signals, generating alarms and various signaling information, etc. The contents of the enclosure may include a tray having a plurality of attachment sections into which optical fiber splices, connectors or standard end fiber terminations can be retained. Optical fiber which is not being coupled within theenclosure110 can also be stored within the enclosure.

FIG. 3 is a cross sectional view of theenclosure assembly100, with theend cap120 partially inserted in theenclosure110. FIG. 4 is an enlarged view of the rim portion of theenclosure assembly100. The fiberoptic enclosure assembly100 includes a fiberoptic enclosure110 having aninner rim114. The top ofrim114 has a diameter that is larger than the diameter of themain part111 of theenclosure110. Aneck section117 transitions from the enlarged diameter of therim section114 to the reduced diameter of themain section111. The slope of the enclosure housing110 changes at twopoints116 and118, which define theneck section117.

Theenclosure110 has anopening113 through which pressurized air can be introduced to the enclosure. A valve (not shown) can be mounted in thehole113, to allow either introduction of air or the measurement of air pressure in theenclosure assembly100.

In the exemplary embodiment, therim114 and themain section111 are substantially vertical in cross section. Theneck section117 is tilted at an angle between about 10 degrees and about 20 degrees from the vertical. Thus, there is a change in slope at location116 (i.e., at the top of the neck section117).

Anend cap120 is shaped to fit theenclosure110. Theend cap120 has a plurality ofcable ports126, through which cables (which may contain optical fibers) enter theenclosure assembly100. Thecable ports126 may have a variety of sizes to accommodate differently sized cables. Prior to installation, each of thecable ports126 has aflat disk126aintegrally attached to the end of the cable port. Theflat disks126aare left onunused cable ports126 until they are used, so that theenclosure assembly100 can be sealed and pressurized. To use one of thecable ports126, the top of the cable port, including theflat disk126ais cut off with a blade, which may be a saw blade. When a cable (not shown) is inserted through acable port126, a seal is placed around the cable port, typically using a sleeve of heat shrink tubing.

Theend cap120 has a thin,pliable membrane124 depending therefrom. Themembrane124 extends into theinner rim114 of theenclosure110 when theend cap120 is in place on the enclosure. Themembrane124 is forced against therim114 when theenclosure100 is pressurized, thereby forming a seal between the membrane and the rim. Theexemplary membrane124 is approximately a cylindrical structure. As best seen in FIG. 4, themembrane124 may have a wedge shaped cross section, and preferably has a thickness that tapers off to a very thin pliable layer at the bottom of the membrane. A flexible material, such as polypropylene, is preferred for the membrane material. Themembrane124 andend cap120 may be formed from a single piece of material.

Although a membrane having a continuous cross-sectional thickness (not shown) may alternatively be used, the wedge shaped profile is advantageous. As the thickness of themembrane124 tapers off to approximately zero thickness, the area moment of inertia of the membrane also tapers off. As a result, the bottom end of themembrane124 is especially pliable, and can be more easily pressed into place against theneck117 of theinner rim114 by air pressure, as described in detail below.

Referring again to FIG. 4, when themembrane124 reaches the top116 of theneck portion117, themembrane124 deforms inwards towards the longitudinal axis of theenclosure110. A gap is formed between the outer circumference ofmembrane124 and theneck section117 of theenclosure110, best shown and described below with reference to FIG.6. Themembrane124 deforms outward to bridge the gap when the enclosure is pressurized.

FIGS. 5 and 6 show a variation of the exemplary embodiment. FIG. 5 shows anenclosure assembly200, including thesame enclosure110 as described above with reference to FIG.3. In FIGS. 5 and 6, a slightly different end cap220 is used. Features of the end cap220 that correspond to features of end cap120 (FIG. 3) are indicated by reference numerals having the same last two digits. Themembrane224 of end cap220 has anelbow225 in the wedge-shaped cross section, best seen in FIG.6. Below theelbow225, the thickness of thebottom portion224bof the membrane decreases more quickly than in thetop section224aof the membrane. Thus,section224bhas a desirable pliability. Further, because the slope of thebottom portion224bof the membrane is greater than the slope at thetop section224aof the membrane, the gap119 (FIG. 6) between themembrane224 and theneck117 of theenclosure110 is greater at the top116 of the neck. Thus, a larger deformation by thebottom portion224bof themembrane224 occurs upon application of pressure.

As shown in FIGS. 5 and 6, to assemble theenclosure assembly200, the end cap220 is inserted all the way into therim114 of theenclosure110. Theenclosure110 and end cap220 haverespective mating parts112 and222, which abut each other when the end cap is completely inserted. Once the end cap220 is installed on theenclosure110, aclamp230 is applied to clamp the end cap220 to theenclosure110, and to keep the end cap from moving. Theclamp230 may be, for example, a V-clamp. U.S. Pat. No. 5,315,489 to McCall et al. is expressly incorporated by reference herein for its teachings on a clamp suitable for use on fiber enclosures. A clamp as described by McCall et al. may be used to clamp theenclosure assembly200.

Thegap119 is present between themembrane224 and theneck portion117 of therim114 before theenclosure assembly200 is pressurized. Themembrane224 moves against therim114 and theneck portion117 to bridge thegap119 when theenclosure assembly200 is pressurized, thereby forming a seal between the membrane and the rim. This sealing action of theenclosure assembly200 occurs automatically upon pressurization of the enclosure, and is not sensitive to any slight misalignment of the end cap, or to the presence of any dirt or grease on the end cap220. So long as the end cap220 is inserted completely, an adequate seal is formed. Thus, the installer can verify the integrity of the seal by visually inspecting theenclosure200 to check whether the end cap is inserted in the enclosure.

Although the method of inserting the end cap220, clamping theassembly200 with theclamp230, and pressurizing theenclosure assembly200 is only described herein with reference to FIGS. 5 and 6, the same steps are performed to close and seal theenclosure assembly100 of FIGS. 3 and 4.

If it is necessary to open the enclosure to reconfigure the equipment or cables therein, the pressure is released through the pressure valve (not shown), theclamp230 is removed, and the enclosure is opened. Upon completion of the reconfiguration, theenclosures100 and200 are closed and sealed by the same method described above.

Although the exemplary embodiment is described in the context of a fiber optic enclosure, the exemplary enclosure is not limited to fiber, and may be used for other electronic equipment, where a water-tight seal is desired.

Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claim should be construed broadly, to include other variants and embodiments of the invention which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.

Claims (20)

What is claimed is:

1. A method for sealing a telecommunications enclosure, comprising the steps of:

(a) placing an end cap on the telecommunications enclosure, the end cap having a pliable membrane depending therefrom, the membrane extending into a rim of the enclosure when the end cap is in place on the enclosure; and

(b) pressurizing the enclosure, so as to force the membrane against the rim, thereby to form a seal between the membrane and the rim.

2. The method of claim1, wherein the membrane is approximately a cylindrical structure.

3. The method of claim1, wherein the membrane and end cap are formed from a single piece of material.

4. The method of claim1, wherein the membrane is formed of polypropylene.

5. The method of claim1, wherein the membrane has a wedge-shaped cross section.

6. The method of claim5, wherein the membrane has an elbow in the wedge-shaped cross section.

7. The method of claim1, wherein a gap is present between the membrane and a neck portion of the rim before step (b) is performed, the membrane moving to bridge the gap when step (b) is performed.

8. The method of claim1, further comprising the step of:

(c) verifying the integrity of the seal by visually inspecting the enclosure to check whether the end cap is inserted in the enclosure.

9. The method of claim1, further comprising the step of clamping the end cap to the enclosure after step (b).

10. The method of claim9, wherein a V-clamp is used to perform the clamping.

11. A sealed telecommunications enclosure assembly, comprising:

a telecommunications enclosure having an inner rim; and

an end cap shaped to fit the enclosure, the end cap having a pliable membrane depending therefrom, the membrane extending into the rim of the enclosure when the end cap is in place on the enclosure, the membrane being forced against the rim when the enclosure is pressurized, thereby to form a seal between the membrane and the rim.

12. The enclosure assembly of claim11, wherein the membrane is approximately a cylindrical structure.

13. The enclosure assembly of claim11, wherein the membrane and end cap are formed from a single piece of material.

14. The enclosure assembly of claim11, wherein the membrane is formed of polypropylene.

15. The enclosure assembly of claim11, wherein the membrane has a wedge-shaped cross section.

16. The enclosure assembly of claim15, wherein the membrane has an elbow in the wedge-shaped cross section.

17. The enclosure assembly of claim11, wherein a gap is present between the membrane and a neck portion of the rim before the enclosure is pressurized, the membrane moving to bridge the gap when the enclosure is pressurized.

18. The enclosure assembly of claim11, further comprising a clamp for clamping the end cap to the enclosure.

19. The enclosure assembly of claim18, wherein the clamp is a V-clamp is used to perform the clamping.

20. The enclosure assembly of claim11, wherein the enclosure has a neck that transitions from a first diameter to a second diameter smaller than the first diameter, the second diameter being smaller than a diameter of the membrane.

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